What Is an Artificial Muscle? A Systemic Approach.

Abstract

Artificial muscles define a large category of actuators we propose to analyze in a systemic framework by considering any artificial muscle as an open-loop stable system for any output which represents an artificial muscle dimension resulting from its "contraction", understood in a broad meaning. This approach makes it possible to distinguish the artificial muscle from other actuators and to specify an original model for a linear artificial muscle, according to the theory of linear systems. Such a linear artificial muscle concept exhibits a constant stiffness independent on its control value. It is shown that a biomimetic actuator, made of two antagonist artificial muscles, requires that artificial muscle static characteristic, even in its most simplified form, is non-linear in the meaning of systems theory, to make possible the control of both actuator position and stiffness. However, we also attempt to show that a linear viscous damping can be a practical way for the dynamic behavior of the artificial muscle to be in relatively good accordance with the so-called Hill curve, interpreted as the dynamic characteristic linking the maximum contraction velocity of the artificial muscle to varying loads lifted against gravity.

A Multistate Friction Model for the Compensation of the Asymmetric Hysteresis in the Mechanical Response of Pneumatic Artificial Muscles

“…Then, a controlled deformation is applied to the PAM through a ball screw actuated by a NEMA 17 stepper motor (Quimat, Hong Kong, China) and the corresponding force f PAM is measured. Figure 2 shows the experimental curves of force vs. length obtained at different values of pressure in the range [1][2][3][4][5][6] [bar]. These curves show asymmetric hysteresis loops.…”

“…Among the actuation technologies implemented in the control systems of soft robots, Pneumatic Artificial Muscles (PAMs) [2] are good candidates as biomimetic, light, safe and efficient actuators for rehabilitation robots, wearable exoskeleton robots and energy-efficient walking humanoids (see [3][4][5][6]).…”

Artificial muscles’ enrichment text: Chemical Literacy Profile of pre-service teachers

“…Artificial muscles is common actuator types are analogous to the natural skeletal muscle (biological muscle) that has the ability to contract in response to a chemical or physical stimulus [17]. In the manufacture of artificial muscles, usually used a material that has properties like biological muscles, are materials that can move when given a stimulus and movements like real muscle.…”

Three-Dimensional Hysteresis Modeling of Robotic Artificial Muscles with Application to Shape Memory Alloy Actuators

“…Robotic artificial muscles are actuators that have similar working mechanisms as biological muscles -they can contract in their cross-sectional directions when activated [8,26]. Compared to conventional actuators such as electric motors and hydraulic actuators, robotic artificial muscles have demonstrated high power-to-weight ratio, high force-to-weight ratio, inherent compliance, and good dynamic range in a muscle-like form factor [8,26,27].…”

“…Compared to conventional actuators such as electric motors and hydraulic actuators, robotic artificial muscles have demonstrated high power-to-weight ratio, high force-to-weight ratio, inherent compliance, and good dynamic range in a muscle-like form factor [8,26,27]. While electric motors and hydraulic actuators can produce large forces and achieve accurate positioning, they often introduce substantial mass, inertia and friction, may require large volumes, and rely on linkages or substantial gear reductions to drive joints.…”